diff --git a/macros/src/check.rs b/macros/src/check.rs
index 464e280ac1..ab86461612 100644
--- a/macros/src/check.rs
+++ b/macros/src/check.rs
@@ -106,10 +106,16 @@ pub fn app(app: &App) -> parse::Result<()> {
     }
 
     // Check that free interrupts are not being used
-    for int in app.interrupts.keys() {
-        if app.free_interrupts.contains_key(int) {
+    for (name, interrupt) in &app.interrupts {
+        let name = if let Some(ref binds) = interrupt.args.binds {
+            binds
+        } else {
+            name
+        };
+
+        if app.free_interrupts.contains_key(name) {
             return Err(parse::Error::new(
-                int.span(),
+                name.span(),
                 "free interrupts (`extern { .. }`) can't be used as interrupt handlers",
             ));
         }
diff --git a/tests/cfail/used-free-interrupt-2.rs b/tests/cfail/used-free-interrupt-2.rs
index f9aab78efd..616d308d0d 100644
--- a/tests/cfail/used-free-interrupt-2.rs
+++ b/tests/cfail/used-free-interrupt-2.rs
@@ -12,8 +12,8 @@ const APP: () = {
     #[init]
     fn init() {}
 
-    #[interrupt(binds = UART0)]
-    fn foo() {} //~ ERROR free interrupts (`extern { .. }`) can't be used as interrupt handlers
+    #[interrupt(binds = UART0)] //~ ERROR free interrupts (`extern { .. }`) can't be used as interrupt handlers
+    fn foo() {}
 
     extern "C" {
         fn UART0();